1995 volvo 940 estate 2.3 lpt

[Laird Scooby]

Originally Posted by Rumbo

Dave…What does the abbreviation RSR stand for please?

Radio Suppression Relay. It is sited in various positions around the engine bay, for example mine is on a bracket in front of the coolant expansion tank just behind the ABS modulator, others are on the NS inner wing and i believe there is a third possible location too. There aren't many relays under the bonnet so if you find one, there's a fair chance it's the RSR - being a 95-on model, yours probably has the ECU controlled cooling fan which is 2-speed controlled by a small module (bigger than a relay) but other cars with an electric cooling fan as well as a viscous one have an identical relay to the RSR, often next to the RSR so they could be swapped as a basic test.

Note that if the RSR is faulty and isn't providing the coil with a +ve feed, the tacho won't pulse while cranking which could give a false indication for the CPS being faulty. Also if those pulses aren't being made, the fuel pump relay won't operate giving no fuel pump action either.

[Rversteeg]

RSR stands for Radio Interference Supression Relay. Its function is to supply 12 V directly from the battery to the fuel injectors (they inject on switching ground on/off). Apperantly if the supply current were to pass the fusebox or ignition key, there is a change of interference with the radio.

The fuel pump relay is in fact a double relay and has quite a central role in the power supply to not just the fuel pump but also injection and ignition system.

This excellent document might be useful:
http://www.stepbystepvolvo.com:60080...20No-Start.pdf

[TonyS9]

Originally Posted by Rumbo

No fluctuating of rpm needle at all when engine is being cranked

It takes about 1s to start so don't expect it immediately. It has to wait for TDC before starting ignition pulses. You need ignition pulses to trigger the pump relay (via the ECU). I'm not 100% sure if the 5V engine speed pulses are sent before TDC (this more specifically triggers the pump). The rpm is driven from actual spark back emf from the coil (so checks ignition amp, crank sensor and coil).

Having said that the pump priming should still happen, so that is an independant test for the pump relay and pump without needing ignition working.

So either you are not waiting or you have a lower level ignition problem like no crank signal aswell.

[TonyS9]

Originally Posted by Rversteeg

RSR stands for Radio Interference Supression Relay. Its function is to supply 12 V directly from the battery to the fuel injectors (they inject on switching ground on/off). Apperantly if the supply current were to pass the fusebox or ignition key, there is a change of interference with the radio.

The fuel pump relay is in fact a double relay and has quite a central role in the power supply to not just the fuel pump but also injection and ignition system.

This excellent document might be useful:
http://www.stepbystepvolvo.com:60080...20No-Start.pdf

The link is dead from my side.

[daveo2002]

RADIO SUPPRESSION RELAY

On my 1998 940 Lpt it's located on the nearside wing near the battery. Black four pin relay with red, black, blue and yellow-blue wires.

Dave

[Rumbo]

After further investigation I’ve found that the fuel pump is making the priming noise,I guess it must be said other faults

[Rversteeg]

The link is dead from my side.

It still works on my side. I suggest to try stepbystepvolvo.com instead and find your way through the website.
Or maybe the link was not correctly transferred:http://www.stepbystepvolvo.com/Resou...20No-Start.pdf

[Laird Scooby]

Originally Posted by Rumbo

After further investigation I’ve found that the fuel pump is making the priming noise,I guess it must be said other faults

That eliminates the fuel pump relay then. Given the other things reported by the RAC run this diags i suggested further up.

[wrinkles]

Fuel pump relay pull it out and carefuly prize the cover off and re solder the joints on the little circuit board job done and it cost nothing saved 20 quid.

[Laird Scooby]

Originally Posted by wrinkles

Fuel pump relay pull it out and carefuly prize the cover off and re solder the joints on the little circuit board job done and it cost nothing saved 20 quid.

Originally Posted by Laird Scooby

That eliminates the fuel pump relay then. Given the other things reported by the RAC run this diags i suggested further up.

If the fuel pump primes, the fuel pump relay is working.